1. Field of the Invention
The present invention generally relates to an image information communication apparatus and, more particularly, to an image information communication apparatus such as a facsimile apparatus which can store image information in a memory in a compressed state and transmit the image information, wherein the storing operation and the transmitting operation can be performed substantially at the same times.
2. Description of the Related Art
When a user attempts to send a plurality of document pages by a facsimile apparatus, the user cannot take the whole document until the transmission of all the document pages is completed. Thus, the user must wait for the completion of transmission while staying nearby the facsimile apparatus.
In order to eliminate such an inconvenience, a facsimile apparatus having a so-called memory transmission function has been used. In this facsimile apparatus, image information corresponding to a plurality of pages of the document to be transmitted via the facsimile apparatus are temporarily stored in a memory. After the image information is stored, the facsimile apparatus calls a remote terminal designated by the user so as to send the image information stored in the memory thereto.
By using the memory transmission function, the user can have the document in his/her hand immediately after the document is read by the facsimile apparatus. Thus, the user no longer has to wait for the completion of the transmission since the subsequent operation can be performed automatically by the facsimile apparatus. This greatly reduces a waiting time of the user, and the operation of the facsimile apparatus is remarkably improved.
In the memory transmission function, the reading and storing operation of the document and the transmitting operation are sequentially performed as shown by a flowchart of FIG. 1. In this method, a time period spent on a single job performed by the facsimile apparatus is a sum of the time periods of a storing operation and a transmitting operation.
The storing operation includes a process for reading an original document by a scanner, a process for encoding and compressing the image data supplied by the scanner and a process for storing the encoded and compressed image data in a memory. The transmitting operation includes a process for calling a remote terminal to perform a predetermined communication protocol and a process for reading the image data in the memory and transmitting the image data to the remote terminal.
Since the storing operation and transmitting operation are almost independent of each other, the storing operation and the transmitting operation may be concurrently performed as shown by a flowchart of FIG. 2. Hereinafter, this operation is referred to as a parallel storing and transmitting operation. Apparently, this operation reduces a time period for a single job performed by the facsimile apparatus by a time period during which the storing operation and the transmitting operation are concurrently performed.
That is, in the parallel storing and transmitting operation, a time period from when the sender side starts to store image data to a time when the receiver side outputs the received image data is reduced. Thus, a time period spent on a single facsimile communication job can be reduced.
As mentioned above, the parallel storing and transmitting operation has an advantage of remarkably reducing the time period spent on sending image data by a facsimile apparatus. However, if the parallel storing and transmitting operation is applied to a facsimile apparatus having a multi-communication function in which a transmitting operation and a receiving operation are concurrently performed, there may be a problem as described below.
That is, in such a condition, if the receiving operation is set in a memory receiving mode, an available area of the memory is increased by deleting a part of image data stored in the memory immediately after the part of the image data is transmitted. This operation is performed for acquiring an area of the memory in which area the following image data to be transmitted can be stored. The memory for storing the image data to be transmitted is also used as a memory for storing the received image data As the image data received from a remote terminal is accumulated in the memory, an available memory area is reduced. This may result in a situation where the parallel storing and transmitting operation cannot be smoothly operated due to an insufficient memory area.
Additionally, in a group 4 facsimile apparatus using ISDN, which has a high transmission speed, as a transmission line, a time period spent on the encoding and compressing operation may become a bottleneck for reducing the storing operation of the image data read by a scanner. This is because a reading speed of the scanner has been increased. If the reading speed of the scanner is faster than the storing operation of the image data read by the scanner, the reading operation of the scanner must be intermittently performed. This operation mode is referred to as an intermittent reading mode. If the scanner is operated in the intermittent reading mode, a continuous reading operation cannot be performed. Thus, there is a possibility that the image data has noise due to frequent stopping of the reading operation. This results in deterioration in a quality of an image output at the receiver side.
In order to eliminate such a problem, it is suggested to provide a buffer memory in which the image data supplied by the scanner is temporarily stored. The stored image data is then processed by the encoding and compressing operation. However, even if the buffer memory is used, there is a possibility that the supply of the encoded and compressed image data is not sufficient for the speed of the transmitting operation especially when the image data corresponds to a photographic image which requires a relatively long time for encoding and compression. When such a condition occurs, raw image data which is not encoded and compressed is supplied to the memory.
In the G3 facsimile communication mode, the image data stored in the memory is always decoded to the raw image data to be stored in a line memory before it is transmitted. The raw image data in the line memory is once again compressed by, for example, a Modified Modified Read (MMR) method. This operation is performed for a part of image data corresponding to each page or each block smaller than a single page. Thus, if the raw image data is mixed with the compressed image data in the memory, there is no problem for the G3 facsimile communication mode. However, in a G4 facsimile communication mode, the image data in the memory is transmitted without being processed by the decoding and encoding operations as is done in the G3 facsimile communication mode. Thus, when the G4 facsimile communication mode is used, it should be determined whether or not the raw image data is mixed with the image data in the memory which is to be transmitted so that the image data will be encoded and compressed again when the image data contains the raw image data.
In a conventional G4 facsimile communication mode, information representing the nature of the image data, which information includes the presence of the raw image data, is added to a part of the image data corresponding to each pages Accordingly, when the G4 facsimile communication mode is used, and if the image data is transmitted by each block, which is smaller than a single page, there is a problem in that it is difficult to recognize whether or not a part of the image data to be transmitted contains the raw data.